Milkweeds and their Natural Plant Communities

The Maryland Native Plant Society hosted a presentation on Milkweeds and their Natural Plant Communities on Tuesday, July 31, 2018, which I attended.  The speakers were Rochelle Bartolomei and Becky Melzer.  Rochelle Bartolomei is the Native Plant Program Manager for Montgomery County Parks. Becky Melzer is the Assistant Plant Program Manager.  Together they responsibly collect local ecotype native seed from county parklands and propagate plants to return to the parks for use at nature centers, stormwater management facilities (SWM), restoration projects, and as donations to various projects.  Since its inception in 2013, the program has generated nearly 100,000 potted plants from seed collection, averaging 21,000 potted plants per annum.  The majority of the plantings have gone to SWM facilities to enhance their surroundings as pollinator meadows.

Over the years these two ladies have documented the natural community structure of old field meadows, where they may occasionally observe common milkweed and/or butterfly milkweed, and on rare occasions the Maryland State rare (S2) purple milkweed in uplands and swamp milkweed in wetlands.  Milkweeds are considered a signature or anchor species of pollinator meadows.

Swamp milkweed has two varieties, one being Asclepias incarnata and the other being Asclepias incarnata variation pulchra (pronounced pullkra).  A. incarnata is a Maryland mountain species and A. pulchra is the coastal plain and Piedmont species, and both being capable of  hybridizing with each other.  A. pulchra has hairy stems, wide leaves and robust flowering, whereas A. incarnata does not have hairy stems, the leaves are narrower, and the flowering head is not as robust or showy as  A. pulchra.  The swamp milkweed is associated with soft rush, beaked panic grass and several other grass, sedge and rush species, joe-pye weed, blue vervain, hibiscus, fall aster and New York ironweed.

Photo of Swamp Milkweed

Common milkweed (Asclepias syriaca) is a great colonizer and can be an aggressive bully in the created pollinator meadow.  Common milkweed tends to self-sow, and readily germinates from de-bearded drill seeding.  Associate plants include wingstem, tall meadow rue, aster, goldenrod, Senna, black-eyed Susan, little bluestem and several other native grass types.  They often interplant with bee balm and coreopsis tickseed sunflowers.  This milkweed has a tap root, finger-sized, carrot-looking roots/tubers and enjoys the hot, open sun.  They perform a July mowing at some locations.

Butterfly milkweed (Asclepias tuberosa), is the shortest of the milkweed species and is often hand planted along the front of meadows and along trails, where it may be enjoyed.  Best to grow with shorter species and is associated with purple love grass, pussy toes and other grassland species.  They grow slow, so they usually plant them in larger, drifts, sweeps and aggregates for their impact.

Photo of Butterfly Milkweed

Purple milkweed (Asclepias purpurascens) is Maryland State rare, and often misdiagnosed as swamp milkweed.  It reaches a height of only two-feet, is hard to grow and prefers diabase or circumneutral soils.  The flowers of purple milkweed are more purple than pink, hence the name.

The two recognized community types of which most pollinator meadows reside, per the The Natural Communities of Maryland: 2016 Natural Community Classification Framework, include:

Andropogon virginicus Ruderal Grassland
Broomsedge Bluestem Ruderal Grassland, also known as Broomsedge Old-field Grassland

Summary:  This association includes herbaceous-dominated vegetation that has been anthropogenically altered and/or maintained, especially on old fields and pastures.  Examples support predominately native species or a mixture of native and exotic species, one of the most dominant or characteristic species being broomsedge and meadow fescue that can dominate fields early in the season.  This is a very common and wide-ranging association that can be quite variable in terms of species composition.  Additional components are other perennial grasses and herbaceous species, most with pioneer or weedy tendencies, the exact composition of which will vary with geography, management history, and habitat.

Schedonorus (arundinaceus, pratensis) Ruderal Grassland
Tall Fescue, Meadow Fescue Ruderal Grassland, also known as Cultivated Grassland

Summary:  This association includes grassland pastures and hayfields, more-or-less cultural, though sometimes no longer actively maintained.  The dominant species in this type are the European “tall or meadow fescues” (Schedonorus spp.) of uncertain and controversial generic placement.  Several other exotic grasses, including redtop, orchardgrass, velvetgrass and Kentucky bluegrass are common associates.  These communities are sometimes nearly monospecific but can also be very diverse and contain many native as well as exotic species of grasses, sedges, and forbs.  Exotic forbs include sericea lespedeza, yarrow, clovers, hedge bindweed, Queen Anne lace, oxeye daisy, yellow oxalis and plantain.  Common native herbs include dogbane, tick trefoil, deertongue, daisy fleabane, wild strawberry, cinquefoil and horse nettle.

Other common grasses of grassland communities include:  Virginia wild rye, big bluestem, little bluestem, indiangrass, barnyard grass, purpletop and red fescue.

I have had multiple contracts to create pollinator meadows for the Navy on federal lands, and have had great success with common and butterfly milkweed used in our hydroseed and drill seed mixes, and yes common milkweed can be aggressive, but it really brings in the insects and directly supports monarch butterflies.


Presentation Handout:  Milkweeds